The present disclosure relates to an electrophotographic image forming apparatus, a laser scanning unit mounted in the image forming apparatus, and a laser scanning method.
In an image forming apparatus, such as a printer, that is capable of forming an image by electrophotography, the light emitted from a light source based on image data is scanned onto an image carrier such as a photosensitive drum by a scanning portion such as a polygon mirror, and an electrostatic latent image corresponding to the image data is formed on the image carrier. In an image forming apparatus of this kind, the light emission timing corresponding to each line of the image data, i.e., the timing of writing an electrostatic latent image, is determined based on the timing of light detection by a light detection portion capable of detecting the light from the light source scanned by the scanning portion.
Meanwhile, an image forming apparatus is known in which the light beams emitted from a plurality of light sources corresponding to a plurality of image carriers are scanned by one scanning portion. In an image forming apparatus of this kind, the timing of writing an electrostatic latent image in each of a color printing mode in which a color image is formed and a monochrome printing mode in which a monochrome image is formed is determined based on the timing of light detection by a light detection portion that is provided so as to correspond to one of the plurality of light sources.